Method for re-profiling at least one running surface of a rail, and corresponding device

ABSTRACT

The invention relates to a method for re-profiling the running surface of a rail, preferably the convex portion of the rail head cross-profile of a rail, especially a railway rail, by peripheral milling. The aim of the invention is to obtain a profile that meets the requirements and has few corrugations. To this end, for producing the profile in a single peripheral grinding step, more than five, preferably nine milling tracks are produced that are oriented in parallel to the longitudinal direction of the rail. Optionally, the running surface, preferably the convex portion of the rail head cross-profile including the running surface is ground afterwards.

[0001] The invention relates to a method for re-profiling by peripheral milling at least one running surface of a rail, preferably the convex portion of the rail head cross-profile of a rail, especially a railway rail, which convex portion exhibits the running surface.

[0002] It is known to re-profile worn rails by peripheral milling, i.e. to provide them with a new profile. For that purpose, the rail head was machined by peripheral milling. In order to somewhat control the costs of a milling cutter, it is known to equip the milling cutter with turning plates mounted to holding devices in turn inserted in recesses in the milling cutter body. In doing so, the turning plates being on a level of the peripheral milling cutter each generate a milling track oriented in the longitudinal direction of the rail. However, for lack of space, the number of turning plates to be attached is limited with peripheral milling cutters of that kind. Therefore, by peripheral milling it was only possible to provide a small number of tracks lying next to each other in the longitudinal direction of the rail and being applied to the rail head by the turning plates. Thereby, a large corrugation is created, and it was necessary to subject the rail head to a smoothing process following upon milling. It is known to equip a peripheral milling cutter for that purpose with a plurality of blades exhibiting the entire desired profile. The plurality of blades is necessary in so far as they ensure that only slight differences in depth occur in the longitudinal direction of the rail. Here, it is disadvantageous that the hollows and points generated by such kind of smoothing extend across the entire cross section that is machined. That causes noise and vibrations when being passed over as well as a decrease in lifetime.

[0003] The invention aims at avoiding those drawbacks and difficulties and has as its object to provide a method of the initially described kind as well as a rail-profile milling cutter for carrying out the method, by means of which it is possible to achieve a minor corrugation both in the longitudinal direction of the rails and in the cross-profile according to the regulations of the railway operators or the railway corporations, respectively, by a milling operation alone so that—for smaller requirements such as, f.i., slower speeds of the railway—a milling operation alone, and for faster speeds, an optionally following grinding operation may suffice.

[0004] In a method of the initially described kind that object is achieved in that, in order to produce the desired profile by a single peripheral milling operation, more than five, preferably nine, milling tracks lying next to each other in the longitudinal direction of the rail are formed and that, in the following, optionally a grinding operation of at least the running surface, preferably the convex portion of the rail head cross-profile, which convex portion exhibits the running surface, is carried out.

[0005] Preferred variants are characterized in the subordinate claims.

[0006] As mentioned above, for greater requirements such as, f.i., faster travelling speeds, the milling operation according to the invention is followed by a grinding operation which is characterized in that, in order to decrease or level the corrugation running in the longitudinal direction of the tracks and, optionally, in order to flatten or level the polygonal line or draft of traverse, respectively, the milled rail is ground, preferably immediately upon milling taking place in the same run, with the axis of the grinding wheel and a plane perpendicular to the longitudinal direction of the rail including an angle deviating from 0°. Preferred variants for said grinding are described in the subordinate claims 6 to 24.

[0007] A rail-profile milling cutter according to the invention for milling at least one running surface of a rail, especially a railway rail, preferably for milling the convex portion of a rail head cross-profile of a rail, for carrying out the method according to one or several of claims 1 to 24 is characterized in that, as a sandwich milling cutter, the milling cutter is configured with a plurality of wheels each of which is provided with turning plates at the periphery.

[0008] Advantageous embodiments are described in the subordinate claims 26 to 30.

[0009] A device for carrying out the method according to the invention is characterized by

[0010] a means for generating a relative motion between the rail and the milling cutter as well as the optionally existing grinding wheel,

[0011] a driving means for the milling cutter as well as a driving means for the grinding wheel in case a grinding wheel is provided,

[0012] a milling cutter according to one or several of claims 25 to 30, and in case of subsequent grinding,

[0013] a positioning of the axis of the grinding wheel in a direction deviating from a plane perpendicular to the longitudinal direction of the rail.

[0014] Suitable variants are contained in the subordinate claims 32 to 43.

[0015] In the following, the invention is explained in more detail by way of two exemplary embodiments with reference to the drawing, wherein

[0016]FIG. 1 shows a side view of a device for carrying out the method according to the invention and

[0017]FIG. 2 shows a schematic top view along the arrow II of FIG. 1.

[0018]FIG. 3 shows a variant of the device for carrying out the method according to the invention.

[0019]FIG. 4 shows the cross section of a railway rail in various conditions of the rail.

[0020]FIG. 5 shows the engagement of the grinding wheel on a railway rail seen in cross section, in accordance with the method according to the invention.

[0021] The rail-profile milling cutter according to the invention is shown in FIGS. 6 to 8, with FIG. 6 illustrating a partial section through the milling cutter in the assembled state,

[0022]FIG. 7 illustrating the individual parts of the milling cutter in an exploded view, and

[0023]FIG. 8 being a side view of a wheel of the milling cutter along the arrow VIII of FIG. 7.

[0024] In FIG. 4, the cross section of a rail 1 is illustrated in various conditions. The rail head 3 situated on the stem of a rail 2 is provided with a convex cross-sectional portion 5 exhibiting the running surface 4 on which the track wheel of a rail vehicle runs, which cross-sectional portion, in its new condition, is illustrated by line A. Due to wear, that convex portion 5 of the cross section of the rail head 3 receives the shape as illustrated by line B. As soon as rail 1 has reached that condition or even earlier, as in accordance with high-speed rails, rail 1 is subjected to finishing so that the convex portion 5 of the rail head 3, at least, however, the running surface 4, regains its original condition, i.e. the original cross-sectional shape—as illustrated by line C—with the best possible approximation in accuracy. Thereby, certain tolerances in the range of from 1 to 3 decimillimeters are to be observed according to the regulations of a railway operator or a railway corporation or a supraregional standard such as cen DRAFT pr EN 13674-1. In doing so, it is essential that the guiding surface 6 of the rail 1 and the running surface 4 are finished.

[0025] As can be seen in FIG. 4, a relatively large amount of material has to be removed according to the wear of the rail, which has to be done as fast and inexpensively as possible in case of laid rails so as to impede the railway traffic as little as possible.

[0026]FIGS. 1 and 2 illustrate a device according to the invention which is arranged in a stationary position and past which the rail 1 to be machined is moved. FIG. 3 illustrates a device according to the invention which is incorporated in a movable facility such as a locomotive engine so that it is feasible to machine rails which already have been laid by means of said device. In that case, the device according to the invention exists in duplicate so that both the left-hand and the right-hand rails can be finished in one passage. Parts and devices of the stationary facility and the movable device which are mutually identical are marked by identical numerals.

[0027]7 denotes a milling unit the rail-profile milling cutter 8 of which is configured as a peripheral milling cutter and is described in greater detail hereinafter. Said milling cutter 8 can be driven via a driving motor 9 and a gear 10 whereby the direction of rotation is chosen such that the rail 1 is machined by the cut-down milling method. Immediately adjacent to the milling unit 7, a grinding unit 11 is provided, the grinding wheel 12 of which can be driven by means of a driving gear 13, preferably also in the direction of rotation of the milling cutter 8 so that down-grinding of the rail 1 is effected. The grinding wheel 12 is equipped with a system for regulating the depth of grinding 14 so that it is feasible to continuously readjust the grinding wheel 12 to the rail 1, according to its wear. Said system for regulating the depth of grinding 14 comprises a measuring system for measuring the continuously decreasing diameter of the periphery of the grinding wheel 12; it can also make use of measuring data gained from measuring the moment of driving.

[0028] Just upon their emergence, both the milling chips and the grinding chips as well as the grinding dust are sucked off via the suction means 15 and 16.

[0029] Just in front of the milling unit 7 and just behing the grinding unit 11, guides 17 for the rail 1 are provided in each case, against which guides the rail 1 can be pressed by means of support rolls 18, whereby it is possible to press at least the running surface 4 of the rail 1, preferably the crown of the rail head 3. Furthermore, lateral guiding rolls 19 engaging the rail head 3 on both sides are provided along the device, whereby the lateral guiding rolls 19 fitting closely to the side of the guiding surface 6 of the rail 1 are fixed in their positions. The rail is pressed against the fixed lateral guiding rolls 19 by the lateral guiding rolls 19 fitting closely to the opposite side, whereby the rail 1 assumes an exact position opposite the milling unit and the grinding unit.

[0030] Between the milling unit 7 and the grinding unit 11, a further guide 20 is provided, which is equipped with a damping device in order to eliminate any vibrations of the rail 1 caused by the milling cutter.

[0031] As can be seen in particular in FIG. 2, the axis 21 of the grinding wheel is inclined by an angle α against a plane 22 perpendicular to the longitudinal direction of the rail, which angle is greater than 0, preferably ranging between 1 and 20° C., depending on the respective condition of the rail 1 prior to grinding. If the rail head 3 has a cross section which, due to milling, approaches the ideal cross section, already before grinding, or if the rail 1, in its new condition, is still provided with a roller skin, the angle α suitably ranges between 5 and 12°, ideally amounting to 8°. However, if the previous state of the cross section has been adjusted to the ideal cross-profile in a less exact manner, f.i., if it has been roughed down only crudely, a smaller angle α, preferably ranging between 1 and 6° C., is suitable for securing an optimal chip removal volume with a long service life of the grinding wheel.

[0032] In its new condition, the grinding wheel 12 has already been pre-profiled, i.e., it exhibits a profile which roughly mates rail 1. For an exact manufacture of said counterprofile, it is advantageous to provide a sharpening means 23 with a grinding stone 24 which can be pressed against the periphery of the grinding wheel 12. Said grinding stone has exactly the desired profile which is to be produced and it also includes angle α together with the grinding wheel. Before grinding of the first rail 1 is started, said grinding stone 24 is pressed against the grinding wheel 12 until the grinding wheel has adopted its profile. While rail 1 is ground, the grinding stone 24 can be lifted from the grinding wheel 12, since the grinding wheel profiles itself at the pre-profile, i.e., at the milled rail-head area or the rail-head surface still provided with the roller skin, respectively. During machining of a rail head 3, the grinding stone may optionally be fitted to the grinding wheel 12 for temporary sharpening.

[0033] Rail 1 may also be used for the adjustment of a profile which exactly mates the grinding wheel 12 provided that it has been milled with sufficient accuracy or still has the roller skin.

[0034] If, as in the illustrated exemplary embodiment, a milled rail-head surface is ground, the profiled grinding wheel 12 only has the most important task of smoothing the waves generated by the milling cutter 8 and of creating an image of traverse grinding.

[0035] By inclining the grinding wheel 12 according to the invention, particularly good conditions of engagement as well as a strong smoothing effect occur. The engagement of the inclined grinding wheel 12 is illustrated in FIG. 5. It is apparent that the inclination creates an advantageous engagement angle, in particular at the point where the convex portion 5 of the rail head 3 meets the side faces 25 of the rail head 3. Those favourable conditions of engagement allow also in those places a sufficiently extensive removal of material with a very good thermal behaviour being provided so that, on the ground surface, burning cannot occur. Furthermore, a very good service life of the grinding wheel 12 is thereby created.

[0036] It can be advantageous if the axis 21 of the grinding wheel 12 is also inclined against the rail's longitudinal central plane of symmetry 26 by an angle β which may have a size of between 1 and 20°.

[0037] If different rail profiles are to be machined by means of the device according to the invention, the axis 21 of the grinding wheel 12 may suitably be arranged so as to be adjustable on the device.

[0038] According to the embodiment illustrated in FIG. 3, the milling unit 7 and the grinding unit 11 are incorporated in a rail-milling line 27. By means of actuators 28, the milling cutter 8 and the grinding wheel 12 are moved approximately vertically against the rail 1 until the guides 17 and 20 rest on the rail head 3. A lateral movement of the grinding unit 11 and the milling unit 7 toward the guiding surface 6 until the lateral guiding rolls 19 rest on the rail head 3 is possible as well.

[0039] The rail-profile milling cutter 8 according to the invention is constructed as a sandwich milling cutter, i.e., it is comprised of wheels 30 each of which is shaped as a ring wheel. As will be described hereinafter, those ring wheels 30 each support a plurality of turning plates 31. These are made of hard metals, ceramics or similar materials. As can be seen in FIG. 6, the ring wheels 30 are fastened to a milling cutter core 32 by means of a screw connection 33 and are centered against each other by means of several centering pins 34 and are secured against each other by means of further screws 35.

[0040] According to the illustrated exemplary embodiment, nine ring wheels 30 are provided, whereby the two external ring wheels 30 support quadruple turning plates the cutting edges of which are of an arcuated shape and serve for milling, i.e. creating a milling track, close to the guiding surface 6. At the outer periphery 36, the ring wheels 30 arranged between the external ring wheels 30 are provided with humps 37 surpassing the outer periphery 36 and manufactured in one piece with the ring wheels 30. Said humps 37 form seats for the quadruple turning plates 31, which, however, exhibit straight cutting edges. Due to the humps 37 provided at the ring wheels 30, spacious chip bags 38 are formed between the turning plates 31.

[0041] All turning plates 31 are fastened to the ring wheels 30 preferably by means of screw connections, clamping joints might be used as well. Each of the cutting edges of the turning plates 31 of the ring wheels 30 arranged between the external ring wheels 30 surpasses with its cutting edge the side faces of the ring wheel 30 to which it is fastened. The turning plates 31 of adjacent ring wheels 30, which turning plates are arranged on the ring wheels 30, are arranged so as to be peripherally offset so that, with respect to the periphery, the turning plates 31 of the neighbouring ring wheel end up lying between the turning plates 31 of the first ring wheel 30.

[0042] By means of the sandwich milling cutter 8 according to the invention, it is possible to mill a great number of milling tracks—even more than nine—extending in the longitudinal direction of the rail 1 onto the rail head 3, whereby it is feasible to achieve an extremely great accuracy of the milled cross-profile, i.e., an extremely close approximation to the ideal cross-profile of the rail head 3. For certain requirements, the rail heads 3 re-profiled by means of the milling cutter 8 according to the invention and/or the milling method according to the invention are sufficient without subsequent grinding being necessary, f.i., for travelling speeds which are not too high. For greater requirements, the milled tracks are subjected to a grinding operation such as described above.

[0043] The essential advantage of the grinding method according to the invention lies in the plurality of adjacent milling tracks which can be milled onto the rail head 3 in a single working process. Particularly advantageously, the milling method according to the invention is combined with the grinding method according to the invention, whereby it is feasible to achieve an extensive removal of material also in case of extremely worn rails as well as a surface which, because of the milling method according to the invention, corresponds to the desired rail profile already to a large extent and which requires only minor grinding, i.e., grinding involving the removal of relatively little material, if any.

[0044] In doing so, it is possible to combine milling and grinding in a single operating process, thereby manufacturing a running surface or a machined portion of the rail head, respectively, fulfilling the greatest requirements in terms of running qualities, lifetime and avoidance of noise. 

1. A method for re-profiling by peripheral milling at least one running surface of a rail, preferably the convex portion of the rail head cross-profile of a rail, especially a railway rail, which convex portion exhibits the running surface, characterized in that, in order to produce the desired profile by a single peripheral milling operation, more than five, preferably nine, milling tracks lying next to each other in the longitudinal direction of the rail are formed and that, in the following, optionally a grinding operation of at least the running surface, preferably the convex portion of the rail head cross-profile, which convex portion exhibits the running surface, is carried out.
 2. A method according to claim 1, characterized in that the two external tracks run according to a curved line in the cross section and the tracks between the external ones run according to a straight line in the cross section so that the rail head cross-profile between the external tracks is configured in the manner of a polygonal line or draft of traverse, respectively.
 3. A method according to claim 1 or 2, characterized in that the corrugations of the tracks running in the longitudinal direction of the rail are arranged so as to be mutually offset so that the valleys and peaks of a track end up as offset in the longitudinal direction against the valleys and peaks of the adjacent tracks.
 4. A method according to one or several of claims 1 to 3, characterized in that the milling of the tracks is carried out by the cut-down milling method.
 5. A method according to one or several of claims 1 to 4, characterized in that, in order to decrease or level the corrugation running in the longitudinal direction of the tracks and optionally in order to flatten or level the polygonal line or draft of traverse, respectively, the milled rail is ground, preferably immediately upon milling taking place in the same run, with the axis of the grinding wheel and a plane perpendicular to the longitudinal direction of the rail including an angle deviating from 0°.
 6. A method according to claim 5, characterized in that the axis of the grinding wheel and the plane perpendicular to the longitudinal direction of the rail include an angle α of between 1 and 20° C.
 7. A method according to claim 6, characterized in that the angle α ranges between 5 and 12°, ideally amounting to about 8°.
 8. A method according to one or several of claims 5 to 7, characterized in that the axis of the grinding wheel and a plane of symmetry lying in the longitudinal direction of the rail include an angle β of about 90°.
 9. A method according to one or several of claims 5 to 7, characterized in that the axis of the grinding wheel and a plane of symmetry lying in the longitudinal direction of the rail include an angle β smaller than 90° and greater than 70°, with said angle β being maintained on the side of the guiding surface of the rail.
 10. A method according to one or several of claims 5 to 9, characterized in that, depending on its wear, the grinding wheel is readjusted, preferably automatically, in the direction toward the rail by regulating the depth of grinding.
 11. A method according to claim 10, characterized in that the depth of grinding is regulated by making use of measuring data gained from measuring the diameter of the grinding wheel surface or by making use of measuring data gained from measuring the moment of driving of the grinding wheel.
 12. A method according to one or several of claims 5 to 11, characterized in that the grinding wheel is profiled by means of a grinding stone, whereby the grinding stone exhibits the profile of at least the running surface of the rail and its longitudinal direction, together with the grinding wheel, includes the same angle α and β as does the rail.
 13. A method according to claim 12, characterized in that, before grinding of the running surface of the rail is started and, subsequently, during grinding, profiling is carried out only optionally and at larger time intervals.
 14. A method according to one or several of claims 5 to 13, characterized in that the relative longitudinal motion between the rail and the milling cutter as well as the grinding wheel is generated by longitudinally displacing the rail relative to the milling cutter and the grinding wheel.
 15. A method according to claim 14, characterized in that, immediately before the engagement of the milling cutter and immediately before the engagement of the grinding wheel, the rail in each case is pressed against a guide directed against the running surface of the rail.
 16. A method according to claim 14, characterized in that the guides are damped in order to avoid vibrations.
 17. A method according to one or several of claims 14 to 16, characterized in that, immediately before the engagement of the milling cutter and immediately before the engagement of the grinding wheel, the rail is pressed against a lateral guide directed against the guiding surface of the rail.
 18. A method according to one or several of claims 14 to 17, characterized in that, immediately upon the engagement of the grinding wheel, the rail is pressed against a guide directed toward the running surface of the rail.
 19. A method according to one or several of claims 14 to 18, characterized in that, immediately upon the engagement of the grinding wheel, the rail is pressed against a lateral guide directed against the guiding surface of the rail.
 20. A method according to one or several of claims 5 to 19, characterized in that, just upon their emergence, the milling and grinding chips are sucked off.
 21. A method according to one or several of claims 5 to 20, characterized in that grinding is carried out by the cut-down method.
 22. A method according to one or several of claims 5 to 12, characterized in that the relative longitudinal motion between the rail and the milling cutter as well as the grinding wheel is performed by longitudinally moving the milling cutter and the grinding wheel along a laid rail.
 23. A method according to claim 22, characterized in that the milling cutter as well as the grinding wheel are moved against the rail up to the point of engagement, whereby the movement is restricted in each case by means of a guide which can be pressed against the running surface of the rail, independently of the system for regulating the depth of grinding.
 24. A method according to claim 22 or 23, characterized in that the milling cutter and the grinding wheel are movable in the direction against the guiding surface of the rail, which movement is restricted in each case by means of a guide directed against the guiding surface of the rail.
 25. A rail-profile milling cutter for milling at least one running surface of a rail, especially a railway rail, preferably for milling the convex portion of a rail head cross-profile of a rail, for carrying out the method according to one or several of claims 1 to 24, characterized in that, as a sandwich milling cutter, the milling cutter is configured with a plurality of wheels each of which is provided with turning plates at the periphery.
 26. A rail-profile milling cutter according to claim 25, characterized in that the milling cutter is comprised of more than five wheels, preferably of nine wheels.
 27. A rail-profile milling cutter according to claim 25 or 26, characterized in that the turning plates of adjacent wheels, which turning plates are arranged on the wheels, are arranged so as to be peripherally offset.
 28. A rail-profile milling cutter according to one or several of claims 25 to 27, characterized in that the turning plates are configured as quadruple turning plates.
 29. A rail-profile milling cutter according to one or several of claims 25 to 28, characterized in that the turning plates are fastened to humps radially protruding outward from the wheels, preferably by means of a screw connection.
 30. A rail-profile milling cutter according to one or several of claims 25 to 29, characterized in that the cutting edges of the turning plates surpass the side faces of the wheel to which they are fastened.
 31. A device for carrying out the method according to one or several of claims 1 to 24, characterized by a means for generating a relative motion between the rail and the milling cutter as well as the optionally existing grinding wheel, a driving means for the milling cutter as well as a driving means for the grinding wheel in case a grinding wheel is provided, a milling cutter according to one or several of claims 25 to 30, and in case of subsequent grinding, a positioning of the axis of the grinding wheel in a direction deviating from a plane perpendicular to the longitudinal direction of the rail.
 32. A device according to claim 31, characterized in that the deviation a of the grinding wheel from the plane perpendicular to the longitudinal direction of the rail amounts to between 1 and 20°.
 33. A device according to claim 32, characterized in that the deviation a amounts to from 5 to 12°, preferably to about 8°.
 34. A device according to one or several of claims 31 to 33, characterized in that the positioning of the axis of the grinding wheel is displaceable from a plane perpendicular to the longitudinal direction of the rail in order to adjust different deviations.
 35. A device according to one or several of claims 31 to 34, characterized in that the positioning of the axis of the grinding wheel is configured such that the axis of the grinding wheel and a plane running through the plane of symmetry of the rail include an angle β of 90° or an angle β of between 90 and 70°.
 36. A device according to one or several of claims 31 to 35, characterized in that a means for readjusting the grinding wheel in the direction toward the rail depending on the wear is provided, which means preferably has a measuring system for evaluating the diameter of the grinding wheel.
 37. A device according to one or several of claims 31 to 36, characterized by a grinding stone which has the profile of at least the running surface of the rail and the longitudinal direction of which includes the same angle α and β against the grinding wheel as does the rail.
 38. A device according to one or several of claims 31 to 37, characterized by a means for moving a rail past the milling cutter and the optionally existing grinding wheel in the direction of the longitudinal axis of the rail.
 39. A device according to claim 38, characterized in that the means comprises a guide directed against the running surface of the rail and a pressing facility for pressing the rail against said guide.
 40. A device according to claim 39, characterized in that the guide is vibration-reduced.
 41. A device according to claim 39 or 40, characterized in that a lateral guide for the rail, which lateral guide is directed against the guiding surface of the rail, as well as a pressing facility for pressing the rail against said lateral guide are provided.
 42. A device according to one or several of claims 31 to 37, characterized in that the milling cutter and the optionally existing grinding wheel are provided on a travelling means displaceable along a laid rail.
 43. A device according to claim 42, characterized in that the travelling means is provided with guides restricting the engagement of the milling cutter as well as of the optionally existing grinding wheel approximately vertically and approximately horizontally and enganging the rail at the running surface and at the guiding surface. 